Frequencies for first 10,000 rows of dfage variable in natl1998 dataset :

     Age of |
     Father |      Freq.     Percent        Cum.
------------+-----------------------------------
         14 |          1        0.01        0.01
         15 |          3        0.03        0.04
         16 |         10        0.10        0.14
         17 |         48        0.48        0.62
         18 |        110        1.10        1.72
         19 |        178        1.78        3.50
         20 |        243        2.43        5.93
         21 |        311        3.11        9.04
         22 |        303        3.03       12.07
         23 |        350        3.50       15.57
         24 |        407        4.07       19.64
         25 |        386        3.86       23.50
         26 |        461        4.61       28.11
         27 |        475        4.75       32.86
         28 |        443        4.43       37.29
         29 |        446        4.46       41.75
         30 |        389        3.89       45.64
         31 |        370        3.70       49.34
         32 |        355        3.55       52.89
         33 |        338        3.38       56.27
         34 |        300        3.00       59.27
         35 |        262        2.62       61.89
         36 |        222        2.22       64.11
         37 |        179        1.79       65.90
         38 |        171        1.71       67.61
         39 |        130        1.30       68.91
         40 |         94        0.94       69.85
         41 |         92        0.92       70.77
         42 |         63        0.63       71.40
         43 |         47        0.47       71.87
         44 |         41        0.41       72.28
         45 |         29        0.29       72.57
         46 |         25        0.25       72.82
         47 |         20        0.20       73.02
         48 |         24        0.24       73.26
         49 |         13        0.13       73.39
         50 |         13        0.13       73.52
         51 |          5        0.05       73.57
         52 |          7        0.07       73.64
         53 |          7        0.07       73.71
         54 |          4        0.04       73.75
         55 |          1        0.01       73.76
         56 |          1        0.01       73.77
         57 |          4        0.04       73.81
         58 |          2        0.02       73.83
         60 |          1        0.01       73.84
         61 |          1        0.01       73.85
         70 |          1        0.01       73.86
         99 |      2,614       26.14      100.00
------------+-----------------------------------
      Total |     10,000      100.00

by Jean Roth , jroth@nber.org , 22 Dec 2015